JP2019156002A - Marine propulsion devise and ship - Google Patents

Abstract

To provide a marine propulsion devise and a ship capable of recovering contraction flow energy generated by propeller rotation.SOLUTION: A marine propulsion devise comprises a propeller provided at the stern, and a duct located at least partially on the wake side of the propeller and with the centerline along the axis of the propeller rotation. The duct has an airfoil shape in the cross section including the centerline and the angle of the airfoil shape chord direction relative to the centerline is 5 degrees or less.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a marine propulsion device and a marine vessel.

  In a ship equipped with a propeller, thrust is obtained by the rotation of the propeller, and at the same time, a flow that does not contribute to the thrust may be generated by the rotation of the propeller. For example, a swirl flow (a flow having a velocity component in the propeller rotation direction) generated behind the propeller due to the rotation of the propeller does not contribute to thrust, and thus such swirl flow can cause energy loss. In this way, a device has been devised to recover the flow energy that is generated by the rotation of the propeller but does not contribute to the thrust to obtain the thrust.

  Patent Documents 1 and 2 disclose a ship in which airfoil-shaped fins are attached to a rudder or a hull located behind a propeller in order to collect the rotational energy of the propeller wake as thrust. The fin receives a rotational flow on the propeller downstream side generated by the rotation of the propeller to generate a force, and a propulsion direction component of the force becomes a thrust, thereby improving the propulsion efficiency of the ship.

  Patent Document 3 discloses a marine propeller including a duct supported by a hull so as to be positioned immediately after the propeller, and a rectifying fixed wing fixed to the inside of the duct. In this marine propeller, the flow having a strong swirling component as the wake of the propeller is captured by the duct and the rectifying fixed wing, and the captured flow is forcibly discharged backward, thereby It is designed to increase.

JP 2014-19199 A JP 2004-262356 A JP-A-8-108890

By the way, on the wake side of the propeller, in addition to the above-described swirl flow, there may be a contracted flow that is directed rearward in the rotational axis direction and directed from the outer side to the inner side in the propeller radial direction. The contracted flow is formed by accelerating the flow inflowing from the outside of the propeller in the radial direction behind the propeller.
This constricted flow also does not contribute to the thrust of a ship or the like as it is, and can be a factor of energy loss. Therefore, it is desirable to recover the energy of the contracted flow and convert it into a thrust of a ship or the like. However, as described above, Patent Documents 1 to 3 describe recovering the energy of the swirling flow generated on the wake side of the propeller, but recovering the energy of the contracted flow and the specifics for that purpose. No arrangement is disclosed.

  In view of the above circumstances, at least one embodiment of the present invention aims to provide a marine vessel propulsion device and a marine vessel that can recover the energy of the contracted flow generated by the rotation of the propeller.

(1) A marine propulsion device according to at least one embodiment of the present invention includes:
A propeller installed at the stern,
A duct located at least partially on the wake side of the propeller and having a center line along the rotation axis of the propeller,
The duct has an airfoil shape in a cross section including the center line,
The angle formed by the cord direction of the airfoil shape with respect to the center line is 0 degree or more and 5 degrees or less.

  According to the configuration of (1), the duct located at least partially is provided on the wake side of the propeller, and the angle formed by the cord direction of the airfoil shape (cross-sectional shape) of the duct with respect to the center line is 0 degree. Since the angle is 5 degrees or less, the angle formed by the cord direction and the direction of the contracted flow flowing into the duct becomes appropriate, and it becomes easy to obtain a thrust in a duct having an airfoil cross section. For this reason, the energy of the contracted flow produced on the propeller downstream side can be effectively recovered, and the energy loss caused by the rotation of the propeller can be reduced.

(2) In some embodiments, in the configuration of (1) above,
When the rotation radius of the propeller is R, the front edge of the duct has a distance measured rearward from the rear edge of the propeller in the axial direction of the propeller of 0.05R or more and 0.5R or less, and the propeller The distance from the rotation axis in the radial direction is within a range of 0.80R to 0.95R.

As a result of intensive studies by the inventor, the contracted flow generated on the posterior side of the propeller has a distance measured rearward from the rear edge of the propeller in the axial direction of the propeller of 0.5 R or less and the rotational axis in the radial direction of the propeller At a position where the distance from the center is 0.80R or more, the inflow angle is relatively large, and at a position where the distance measured backward from the trailing edge of the propeller in the axial direction of the propeller is shorter than 1.0R, the flow velocity is relatively I found it big.
In the configuration of the above (2), the distance of the front edge of the duct measured rearward from the rear edge of the propeller in the axial direction of the propeller is 0.05R or more and 0.5R or less, and the radial direction of the propeller Since the distance from the rotation axis is within the range of 0.80R or more and 0.95R or less, the energy of the contracted flow generated on the propeller downstream side is avoided while avoiding the interference between the front edge of the duct and the propeller. It can be recovered more effectively.

(3) In some embodiments, in the above configuration (1) or (2),
The duct is supported by a front end portion of a ladder horn fixed to the hull.

  According to the configuration of the above (3), the configuration of the above (1) can be realized by the duct supported by the front end portion of the ladder horn fixed to the hull.

(4) In some embodiments, in the configuration of (3) above,
Of the uppermost part of the duct, the part from the rear edge of the duct to the first position in the center line direction forms a connection part with the ladder horn,
The first position is a position in which the distance from the rear edge of the duct is 0.3L or more and 0.5L or less in the centerline direction when the length of the duct in the centerline direction is L. .

  According to the configuration of (4) above, since the length in the center line direction occupied by the connection portion with the ladder horn is 0.3 L or more among the uppermost portion of the duct, the duct is securely connected to the ladder horn. Can do. In addition, since the length is 0.5L or less, at the uppermost part of the duct, it is possible to sufficiently secure a part that forms the airfoil (that is, a part of the uppermost part of the duct that is ahead of the connection part), It is possible to suppress the reduction of the ducted energy recovery performance of the duct.

(5) In some embodiments, in the above configuration (1) or (2),
The duct is supported at the bottom of the hull.

  According to the configuration of (5), the configuration of (1) can be realized by the duct supported at the bottom of the hull.

(6) In some embodiments, in any one of the above configurations (1) to (5),
When the rotation radius of the propeller is R, the front edge of the duct has a distance measured rearward from the rear edge of the propeller in the axial direction of the propeller of 0.05 R or more and 0.2 R or less, and the propeller The distance from the rotation axis in the radial direction is within a range of 0.80R to 0.95R.

As a result of intensive studies by the inventor, the contracted flow generated on the posterior side of the propeller has a distance measured rearward from the rear edge of the propeller in the axial direction of the propeller of 0.5 R or less and the rotational axis in the radial direction of the propeller At a position where the distance from the center is 0.80R or more, the inflow angle is relatively large, and at a position where the distance measured backward from the trailing edge of the propeller in the axial direction of the propeller is shorter than 1.0R, the flow velocity is relatively In addition, it was found that the inflow angle of the above-mentioned contraction flow is larger at a position where the distance measured backward from the rear edge of the propeller in the axial direction of the propeller is 0.2 R or less.
In this regard, in the configuration of (6) above, the distance measured from the rear edge of the propeller in the axial direction of the propeller to the rear from the rear edge of the propeller is 0.05 R or more and 0.2 R or less, and the radius of the propeller Since the distance from the rotating shaft in the direction is within the range of 0.80R or more and 0.95R or less, the contracted flow generated on the propeller downstream side while avoiding the interference between the front edge of the duct and the propeller. The energy can be recovered more effectively.

(7) In some embodiments, in the configuration of (1) or (2) above,
The duct is supported by a steering plate provided so as to be rotatable with respect to the hull.
When the rotation radius of the propeller is R, the front edge of the duct is located within a range in which the distance measured backward from the rear edge of the propeller in the axial direction of the propeller is 0.3R or more and 0.5R or less. .

  In the configuration of (7), the duct can be rotated together with the rudder plate, so that resistance during turning can be reduced, and the front edge of the duct is rearward from the rear edge of the propeller in the axial direction of the propeller. Since the distance measured in the above is located within the range of 0.3R or more and 0.5R or less, interference between the duct and the propeller can be avoided. Therefore, according to the configuration of the above (7), while reducing the resistance at the time of turning, effectively avoiding the interference between the duct and the propeller, the energy of the contracted flow generated on the rear side of the propeller can be effectively recovered. Can do.

(8) In some embodiments, in the configuration of (7) above,
In the axial direction of the propeller, the minimum distance between the rear edge of the duct and the front end portion of the ladder horn to which the rudder plate is attached is 0.02R or more and 0.3R or less.

  According to the configuration of (8) above, the minimum distance between the rear edge of the duct and the front end portion of the rudder horn is 0.02R or more, so that interference between the duct and the steering plate can be avoided, and Since the minimum distance of 0.3R or less is sufficient, it is possible to secure a sufficient length in the direction of the center line of the duct, and to easily secure an installation space for a member for attaching the duct to the rudder plate.

(9) In some embodiments, in the above configuration (7) or (8),
The duct is supported via a protrusion that protrudes from the rudder plate in the direction of the rotation axis.

  According to the configuration of (9) above, since the duct is supported via the protruding portion protruding in the direction of the rotation axis from the rudder plate, the energy of the hub vortex generated from the propeller boss portion by the protruding portion is also obtained. While collecting, the above-mentioned contracted energy can be collected by the duct.

(10) In some embodiments, in the configuration of (1) above,
When the rotation radius of the propeller is R, the front edge of the duct is between the second position and the third position in the axial direction of the propeller, and the distance from the rotation axis is 1 in the radial direction of the propeller. Located within the range of greater than 0.0R and less than or equal to 1.2R,
The second position is a position where a distance measured forward from a rear edge of the propeller in the axial direction is 0.4R,
In the third position, a distance measured rearward from the trailing edge of the propeller in the axial direction is 0.05R.

  According to the configuration of (10) above, the front edge of the duct is between the second position and the third position described above in the axial direction of the propeller, and the distance from the rotating shaft in the radial direction of the propeller is from 1.0R. Since it is located within the range of 1.2 R or less, at least a part of the tip portion of the propeller can be covered with the duct. Thereby, the fluctuating pressure which acts on a ship bottom with rotation of a propeller can be reduced.

(11) In some embodiments, in the configuration according to any one of (1) to (10) above,
It further includes at least one stator fin extending radially inside the duct.

  According to the above configuration (11), since at least one stator fin is provided inside the duct, the above-mentioned contracted flow is recovered by the duct while collecting the energy of the swirling flow generated by the rotation of the propeller by the stator fin. Energy can be recovered.

(12) A ship according to at least one embodiment of the present invention includes the marine propulsion device according to any one of (1) to (11).

  According to the configuration of (12), the duct located at least partially is provided on the downstream side of the propeller, and the angle formed by the cord direction of the airfoil shape (cross-sectional shape) of the duct with respect to the center line is 5 degrees. As described below, the angle formed by the cord direction and the direction of the contracted flow flowing into the duct becomes appropriate, and it becomes easy to obtain thrust in the duct having the airfoil cross section. For this reason, the energy of the contracted flow produced on the propeller downstream side can be effectively recovered, and the energy loss caused by the rotation of the propeller can be reduced.

  According to at least one embodiment of the present invention, a marine propulsion device and a marine vessel capable of recovering the energy of the contracted flow generated by the rotation of the propeller are provided.

It is the schematic of an example of the ship provided with the ship propulsion apparatus concerning one Embodiment. It is the schematic which shows the structure of the propulsion apparatus (marine propulsion apparatus) which concerns on one Embodiment. It is a figure which shows the structure of the duct which concerns on one Embodiment. It is the schematic which shows the structure of the propulsion apparatus (marine propulsion apparatus) which concerns on one Embodiment. It is a schematic perspective view of the propulsion apparatus (marine propulsion apparatus) shown in FIG. It is the schematic which shows the structure of the propulsion apparatus (marine propulsion apparatus) which concerns on one Embodiment. It is the schematic which shows the structure of the propulsion apparatus (marine propulsion apparatus) which concerns on one Embodiment. It is the schematic which shows the structure of the propulsion apparatus (marine propulsion apparatus) which concerns on one Embodiment. It is the schematic which shows the structure of the propulsion apparatus (marine propulsion apparatus) which concerns on one Embodiment. It is the schematic which looked at the propulsion apparatus (marine propulsion apparatus) shown in FIG. 9 from the axial direction. It is a graph which shows an example of the relationship between the axial direction position of a propeller back flow side, and the inflow angle of a contracted flow. It is a graph which shows an example of the relationship between a radial direction position, the flow velocity and inflow angle of a contracted flow.

  Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.

  Drawing 1 is a schematic diagram of an example of a ship provided with a marine propulsion device concerning one embodiment. As shown in the figure, the ship 1 includes a hull 2, a propulsion device 3 (marine propulsion device) for applying thrust to the hull 2, and a rudder 4 for adjusting the traveling direction of the hull 2. Yes.

The hull 2 includes a bow 2 a that is a portion positioned forward, a stern 2 b that is a portion positioned rearward, and a bottom portion 9.
The rudder 4 includes a ladder horn 6 fixed to the stern 2b of the hull 2, a rudder plate 7 supported by the rudder horn 6, and a rudder shaft 5 for rotating the rudder plate 7. The rudder shaft 5 is connected to the rudder plate 7 at one end side, and is driven by a driving device (not shown) so as to be rotatable around a rotation shaft along the vertical direction. That is, the rudder plate 7 can rotate with respect to the hull 2 together with the rudder shaft 5.

  The propulsion device 3 includes a propeller 8 provided on the stern 2b, and a duct 10 located at least partially on the wake side of the propeller 8 (that is, behind the propeller 8). The propeller 8 is configured to be driven to rotate by a driving device (not shown) to generate thrust for propelling the hull 2.

  Hereinafter, the propulsion device 3 (marine propulsion device) according to some embodiments will be described in more detail.

  FIG. 2 is a schematic diagram illustrating the configuration of the propulsion device 3 according to some embodiments. In FIG. 2, a part of the duct 10 is shown as a cross section.

As shown in FIG. 2, the duct 10 is a tubular member having a center line Q in the direction along the rotation axis O of the propeller 8, and has a front edge 12 and a rear edge 14 at both ends in the center line direction.
A cross section (see the hatched portion in FIG. 2) along the center line Q of the duct 10 has an airfoil shape. That is, the leading edge 12 and the trailing edge 14 of the duct 10 that is a tubular member are a set of leading and trailing edges of the airfoil shape of the cross section of the duct 10, respectively.
The angle θ1 formed by the cord direction of the airfoil shape of the cross section of the duct 10 with respect to the center line Q is 5 degrees or less.

In the duct 10, the lift FL according to the angle formed by the direction of the flow flowing into the duct 10 with respect to the cord direction (the direction connecting the leading edge 12 and the trailing edge 14; the direction of the straight line L 1 in FIG. 2). 2), and the axial component of the lift FL acts on the ship 1 as the thrust FT (see FIG. 2).
Here, in order to effectively obtain the thrust FT from the contracted flow fc (see FIG. 2) generated by the rotation of the propeller 8, the airfoil cord direction of the duct 10 and the contracted flow fc are applied to the leading edge 12 of the duct 10. It is desirable that the inflow direction (the direction of arrow A in FIG. 2) is shifted to some extent, and the angle θ2 (attack angle) formed by these two directions is an appropriate size. On the other hand, if the angle θ1 (see FIG. 2) formed by the cord direction (the direction of the straight line L1) with respect to the direction of the center line Q (the direction of the straight line L0 in FIG. 2) is too large, the angle of attack becomes excessive. Since the flow is disturbed near the blade surface and loss is likely to occur, the cord direction described above is preferably a direction along the center line Q.

  In this regard, in the above-described embodiment, the angle θ1 formed by the cord direction (the direction of the straight line L1) of the airfoil shape (cross-sectional shape) of the duct 10 with respect to the center line (the direction of the straight line L0) is set to 5 degrees or less. The angle θ2 formed by the cord direction and the direction of the contracted flow fc flowing in the duct 10 (the direction of the arrow A) becomes an appropriate size, and the thrust FT is easily obtained in the duct 10 having an airfoil cross section. For this reason, the energy of the contracted flow fc generated on the downstream side of the propeller 8 can be effectively recovered, and the energy loss due to the rotation of the propeller 8 can be reduced.

In the exemplary embodiment shown in FIG. 2, the relationship between the radius b at the leading edge 12 of the duct 10 and the radius h at the trailing edge 14 is b> h, but in other embodiments, the relationship between FIG. As shown, the above-mentioned radius b and radius h may satisfy b <h, or b = h, although not particularly shown. In any of the embodiments, the angle θ1 (0 ° ≦ θ1 ≦) formed by the cord direction (direction of the straight line L1) of the airfoil shape (cross-sectional shape) of the duct 10 with respect to the direction of the center line Q (direction of the straight line L0). 90 °) is 0 degree or more and 5 degrees or less.
FIG. 3 is a diagram illustrating a configuration of the duct 10 according to an embodiment.

  Further, although the illustrated duct 10 has a cylindrical shape, in some embodiments, the duct 10 may have a shape including a cylindrical portion. In one embodiment, the duct 10 may have a shape in which a cylinder is divided in half.

  The propulsion device 3 according to some embodiments may further have the following characteristics.

4 and 6 to 9 are schematic views showing the configuration of the propulsion device 3 according to the embodiment, respectively. FIG. 5 is a schematic perspective view of the propulsion device 3 shown in FIG. 10 is the schematic which looked at the propulsion apparatus 3 shown in FIG. 9 from the axial direction.
In FIGS. 4 to 10 and the following description, R is the rotation radius of the propeller 8.

In some embodiments, for example, as shown in FIGS. 4 and 5, the duct 10 may be supported by the front end 6 a of the ladder horn 6 fixed to the hull 2.
In the exemplary embodiment shown in FIGS. 4 and 5, the duct 10 is connected to the ladder horn 6 at the connection 16. The connecting part 16 may be formed on the uppermost part 11 of the duct 10. The duct 10 and the ladder horn 6 may be joined by welding, for example.

In some embodiments, the duct 10 may be supported on the bottom 9 of the hull 2, for example, as shown in FIGS. 6, 8 and 9.
In the exemplary embodiment shown in FIGS. 6, 8, and 9, the duct 10 is attached to the bottom portion 9 of the hull 2 via struts 18 extending in the vertical direction.

In some embodiments, for example, as illustrated in FIG. 7, the duct 10 may be supported by a rudder plate 7 that is rotatable with respect to the hull 2.
In the exemplary embodiment shown in FIG. 7, the duct 10 is supported by the rudder plate 7 via a protrusion 22 that projects from the rudder plate 7 toward the bow in the direction of the rotation axis O of the propeller. A lower end surface of a strut 24 extending in the vertical direction is fixed to the upper surface of the protrusion 22. The upper end surface of the strut 24 is fixed to the inner peripheral surface of the upper portion of the duct 10. In this way, the duct 10 is supported by the rudder plate 7 via the protrusion 22 and the strut 24.

  In the exemplary embodiments shown in FIGS. 4 to 7 among the above-described embodiments, the front edge 12 of the duct 10 has a distance a measured rearward from the rear edge of the propeller 8 in the axial direction of the propeller 8. The distance b from the rotation axis O in the radial direction of the propeller 8 (that is, the radius b at the leading edge 12 of the duct 10) is in the range of 0.80R to 0.95R. To position.

Here, FIG. 11 shows the axial position (x / R) on the wake side of the propeller at several radial positions (5 points within a range of r / R of 0.2 to 1.0) and the contraction. It is a graph which shows an example of the relationship with the inflow angle of a flow. 11 indicates the ratio x / R between the distance x measured rearward from the rear edge of the propeller 8 and the rotation radius R of the propeller 8, and the vertical axis indicates the flow inflow angle. The inflow angle of the axial flow is 0 °, and the inflow angle of the flow from the radially outer side to the inner side in the direction orthogonal to the axial direction is 90 °. Further, r is a radial distance from the rotation axis O of the propeller 8.
Further, FIG. 12 shows the radial position r / R (horizontal axis) at the axial position of x / R = 0.2 (that is, the position 0.2R rearward from the rear edge of the propeller 8) and the contracted flow. It is a graph which shows an example of the relationship between a flow velocity (left vertical axis) and an inflow angle (right vertical axis).

From the graph of FIG. 11, when the radial position r / R is in the range of 0.2 to 1.0, when r / R is 1.0, the inflow angle of the contracted flow is the largest regardless of the axial position. It can be seen that when r / R is in the range of 0.6 to 1.0, the inflow angle tends to increase as r / R increases.
From the graph of FIG. 11, on the wake side of the propeller 8, the smaller the distance from the rear edge of the propeller 8 (that is, the smaller x / R), the larger the inflow angle, and x / R is 0.5 or less. It can be seen that the inflow angle is large to a certain extent, and the inflow angle is particularly large in the range where x / R is 0.2 or less.
12, at the axial position where x / R = 0.2 where the inflow angle of the contracted flow is large, the flow velocity is relatively large when the radial position is less than 1.0, and r It can be seen that when / R exceeds 1.0, the flow rate rapidly decreases.

  That is, from FIG. 11 and FIG. 12, the contracted flow generated on the posterior side of the propeller 8 has a distance measured backward from the rear edge of the propeller 8 in the axial direction of the propeller 8 to 0.5 R or less and the radius of the propeller 8. When the distance b from the rotation axis O in the direction is 0.80R or more, the inflow angle is relatively large, and the distance a measured backward from the rear edge of the propeller 8 in the axial direction of the propeller 8 is from 1.0R. It was also found that the flow velocity was relatively large at a short position.

  Here, when the duct 10 is at least partially disposed on the wake side of the propeller 8, the thrust generated in the duct 10 can be effectively increased by increasing the inflow angle to a certain extent and appropriately setting the angle of attack of the duct 10. Can be obtained. Further, the thrust generated in the duct 10 can be increased by arranging the front edge 12 of the duct 10 at a position where the flow velocity is larger.

  In this regard, in the exemplary embodiment shown in FIGS. 4 to 7, as described above, the distance a between the leading edge 12 of the duct 10 and the trailing edge of the propeller 8 in the axial direction of the propeller 8 is set to 0.5R. The distance b between the rotation axis O in the radial direction of the propeller 8 and the front edge 12 of the duct 10 is set to 0.80R or more and 0.95R or less, so that the inflow angle of the contracted flow with respect to the duct 10 is relatively large. can do. Further, since the distance a between the front edge 12 of the duct 10 and the rear edge of the propeller 8 in the axial direction of the propeller 8 is set to 0.05 R or more, interference between the front edge 12 of the duct 10 and the propeller 8 is avoided. be able to. Therefore, while avoiding interference between the front edge 12 of the duct 10 and the propeller 8, it is possible to effectively recover the energy of the contracted flow generated on the propeller downstream side.

  In some embodiments, the distance a between the front edge 12 of the duct 10 and the rear edge of the propeller 8 in the axial direction of the propeller 8 may be set shorter, for example, 0.2 R or less. That is, the distance a measured from the rear edge of the propeller 8 to the rear side of the propeller 8 in the axial direction of the propeller 8 is 0.05R or more and 0.2R or less, and from the rotation axis O in the radial direction of the propeller 8. The distance b may be within the range of 0.80R to 0.95R.

  As can be seen from the graph of FIG. 11, when the distance a between the front edge 12 of the duct 10 and the rear edge of the propeller 8 in the axial direction of the propeller 8 is 0.2R or less, the distance a is 0.5R. The inflow angle is larger than the position. For this reason, it is considered that a larger thrust can be obtained in the duct 10 by setting the position of the front edge 12 of the duct 10 in the axial direction to a position where the distance a is 0.2R or less. Therefore, the energy of the contracted flow generated on the rear side of the propeller can be recovered more effectively.

  For example, in the embodiment shown in FIGS. 4 to 5 and 6, unlike the embodiment shown in FIG. 7, the duct 10 is installed so as not to move with respect to the hull 2. It is not necessary to consider the interference with 8, and the distance a between the duct 10 and the propeller 8 can be set relatively short. Therefore, by setting the above-mentioned distance a to 0.2 R or less, the energy of the contracted flow generated on the propeller downstream side can be recovered more effectively.

When the uppermost part 11 of the duct 10 is connected to the ladder horn 6 as in the exemplary embodiment shown in FIGS. 4 to 5, the rearward of the duct 10 in the direction of the center line of the uppermost part 11 of the duct 10. A portion from the edge 14 to the first position P1 where the ladder horn 6 and the duct 10 are in contact with each other may form a connection portion 16 with the ladder horn 6.
In this case, the length in the center line direction of the duct 10 is L (see FIG. 4), and the first position P1 described above has a distance from the rear edge 14 of the duct 10 in the direction of the center line Q of 0.3 L or more. The position may be 0.5 L or less. In other words, in the uppermost part 11 of the duct 10, a part of 30% or more and 50% or less on the rear edge 14 side in the center line direction may form the connection part 16 with the ladder horn 6.

  Thus, the duct 10 is reliably connected to the ladder horn 6 by setting the length in the center line direction occupied by the connecting portion 16 with the ladder horn 6 in the uppermost portion 11 of the duct 10 to 0.3 L or more. be able to. In addition, by setting the length to 0.5 L or less, a portion that forms an airfoil in the uppermost portion 11 of the duct 10 (that is, a portion of the uppermost portion 11 of the duct 10 in front of the connecting portion 16). Sufficiently can be secured, and the reduction of the contracted energy recovery performance of the duct 10 can be suppressed.

  When the duct 10 is supported by the rudder plate 7 provided to be rotatable with respect to the hull 2 as in the exemplary embodiment shown in FIG. 7, the front edge 12 of the duct 10 is in the axial direction of the propeller 8. The distance a measured backward from the rear edge of the propeller may be within a range of 0.3R to 0.5R.

  Thus, if the duct 10 can be rotated together with the rudder plate 7, the resistance at the time of turning can be reduced. In addition, interference between the duct 10 and the propeller 8 can be avoided by setting the above-described distance a to be 0.3R or more, and by setting the above-described distance a to be 0.5R or less, the front of the duct 10 can be avoided. By reducing the distance between the edge 12 and the propeller 8 as much as possible, the inflow angle of the contracted flow into the duct 10 can be made relatively large. Therefore, while reducing resistance at the time of turning, avoiding interference with the duct 10 and the propeller 8, it is possible to effectively recover the energy of the contracted flow generated on the propeller downstream side.

  Further, in the embodiment in which the duct 10 is supported by the rudder plate 7 provided to be rotatable with respect to the hull 2 as in the exemplary embodiment shown in FIG. 7, the duct 10 is arranged in the axial direction of the propeller 8. 0.02R or more and 0.3R or less may be sufficient as the minimum distance e (refer FIG. 7) between the rear edge 14 and the front-end part 6a of the ladder horn 6 to which the rudder plate 7 was attached.

  Thus, since the minimum distance e between the rear edge 14 of the duct 10 and the front end portion 6a of the ladder horn 6 is 0.02R or more, interference between the duct 10 and the rudder plate 7 can be avoided, Since the above-mentioned minimum distance e is set to 0.3 R or less, a sufficient length in the center line direction of the duct 10 can be secured, and a member for attaching the duct 10 to the rudder plate 7 (for example, the implementation shown in FIG. 7). It becomes easy to secure the installation space of the struts 24) in the form.

  In the exemplary embodiment shown in FIG. 7, as described above, the duct 10 is supported via the protruding portion 22 protruding from the rudder plate 7 in the direction of the rotation axis O of the propeller 8. While the energy of the hub vortex generated from the propeller boss portion 30 is also recovered by the protrusion 22, the energy of the above-described contracted flow can be recovered by the duct 10.

  As shown in FIG. 7, the front edge 23 of the protrusion 22 described above may have a spherical shape. In this case, since the protrusion 22 receives the wake from the propeller 8 at the spherical front edge 23, the fluid loss can be further reduced.

  In the exemplary embodiment shown in FIG. 8, the leading edge 12 of the duct 10 has a second position P2 (see FIG. 8) which is the position of the end of the stern bearing in the axial direction of the propeller 8 and the hull position of the propeller boss. And a distance g from the rotation axis O in the radial direction of the propeller 8 is within a range of greater than 1.0R and less than or equal to 1.2R. Here, the second position P2 is a position where the distance measured forward from the rear edge of the propeller 8 in the axial direction of the propeller 8 is 0.4R, and the third position P3 is the position of the propeller 8 in the axial direction of the propeller 8. The distance measured backward from the trailing edge is a position of 0.05R.

  In this case, the front edge 12 of the duct 10 has a distance g between the above-described second position P2 and the third position P3 in the axial direction of the propeller 8 and from the rotation axis O in the radial direction of the propeller 8 is 1.0R. Since it is located within the range of 1.2 R or larger, at least a part of the tip portion of the propeller 8 can be covered by the duct 10. Thereby, the fluctuating pressure which acts on the bottom part 9 of the hull 2 with rotation of the propeller 8 can be reduced.

In some embodiments, for example, as shown in FIGS. 9 to 10, the propulsion device 3 may further include at least one stator fin 28 that extends radially inside the duct 10.
In the exemplary embodiment shown in FIGS. 9 to 10, the radial direction of the duct 10 is between the outer peripheral surface of the hub member 27 provided along the center line Q of the duct 10 and the inner peripheral surface of the duct 10. A plurality of stator fins 28 extending along the line are provided. As shown in FIG. 9, the cross section of the stator fin 28 may have an airfoil shape.

  In this case, since at least one stator fin 28 is provided inside the duct 10, the energy of the above-described contracted flow is recovered by the duct 10 while collecting the energy of the swirling flow generated by the rotation of the propeller 8 by the stator fin 28. Can be recovered.

  If only the stator fin 28 is used without using the duct 10 in order to recover the energy of the swirling flow on the wake side of the propeller 8, the swirling component is changed as indicated by a broken line arrow f <b> 2 shown in FIG. 10. Since the flow it has escapes radially outward, the effect of collecting the swirling flow is limited. In this regard, as in the embodiment shown in FIG. 10, by using the duct 10 and the stator fin 28 together, it is possible to suppress the flow from escaping radially outward by the duct 10 (see the solid line arrow f <b> 1). The energy recovery effect can be improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, The form which added the deformation | transformation to embodiment mentioned above and the form which combined these forms suitably are included.

In this specification, an expression representing a relative or absolute arrangement such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial”. Represents not only such an arrangement strictly but also a state of relative displacement with tolerance or an angle or a distance to obtain the same function.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
In this specification, expressions representing shapes such as quadrangular shapes and cylindrical shapes not only represent shapes such as quadrangular shapes and cylindrical shapes in a strict geometric sense, but also within a range where the same effects can be obtained. In addition, a shape including an uneven portion or a chamfered portion is also expressed.
In this specification, the expression “comprising”, “including”, or “having” one constituent element is not an exclusive expression for excluding the existence of another constituent element.

1 ship 2 hull 2a bow 2b stern 3 propulsion device (marine propulsion device)
4 rudder 5 rudder shaft 6 rudder horn 6a front end 7 rudder plate 8 propeller 9 bottom 10 duct 11 uppermost part 12 front edge 14 rear edge 16 connection 18 strut 22 protrusion 23 front edge 24 strut 27 hub member 28 stator fin 30 propeller Boss part A Arrow FL Lifting force FT Thrust O Rotation axis P1 First position P2 Second position P3 Third position Q Center line R Rotation radius a Distance in the axial direction between the duct leading edge and the propeller trailing edge b Duct leading edge and propeller rotation Radial distance from the shaft e Minimum distance fc between the trailing edge of the duct and the ladder horn Constriction g Radial distance between the leading edge of the duct and the propeller rotating shaft h Radial distance between the trailing edge of the duct and the propeller rotating shaft

Claims (12)

A propeller installed at the stern,
A duct located at least partially on the wake side of the propeller and having a center line along the rotation axis of the propeller,
The duct has an airfoil shape in a cross section including the center line,
The marine propulsion device characterized in that an angle formed by the cord direction of the airfoil shape with respect to the center line is 5 degrees or less. When the rotation radius of the propeller is R, the front edge of the duct has a distance measured rearward from the rear edge of the propeller in the axial direction of the propeller of 0.05R or more and 0.5R or less, and the propeller 2. The marine propulsion device according to claim 1, wherein a distance from the rotation shaft in a radial direction is within a range of 0.80R to 0.95R. The marine propulsion device according to claim 1, wherein the duct is supported by a front end portion of a ladder horn fixed to the hull. Of the uppermost part of the duct, the part from the rear edge of the duct to the first position in the center line direction forms a connection part with the ladder horn,
The first position is a position in which the distance from the rear edge of the duct is 0.3L or more and 0.5L or less in the centerline direction when the length of the duct in the centerline direction is L. The marine propulsion device according to claim 3. The marine propulsion device according to claim 1, wherein the duct is supported by a bottom portion of a hull. When the rotation radius of the propeller is R, the front edge of the duct has a distance measured rearward from the rear edge of the propeller in the axial direction of the propeller of 0.05 R or more and 0.2 R or less, and the propeller The marine propulsion device according to any one of claims 1 to 5, wherein a distance from the rotary shaft in a radial direction is within a range of 0.80R to 0.95R. The duct is supported by a steering plate provided so as to be rotatable with respect to the hull,
When the rotation radius of the propeller is R, the front edge of the duct is located within a range in which the distance measured backward from the rear edge of the propeller in the axial direction of the propeller is 0.3R or more and 0.5R or less. The marine propulsion device according to claim 1, wherein the marine propulsion device is provided. The minimum distance between the rear edge of the duct and the front end of the rudder horn to which the rudder plate is attached in the axial direction of the propeller is 0.02R or more and 0.3R or less. Item 8. A marine propulsion device according to item 7. The marine propulsion device according to claim 7 or 8, wherein the duct is supported via a protruding portion that protrudes from the rudder plate in the direction of the rotation shaft. When the rotation radius of the propeller is R, the front edge of the duct is between the second position and the third position in the axial direction of the propeller, and the distance from the rotation axis is 1 in the radial direction of the propeller. Located within the range of greater than 0.0R and less than or equal to 1.2R,
The second position is a position where a distance measured forward from a rear edge of the propeller in the axial direction is 0.4R,
2. The marine propulsion device according to claim 1, wherein the third position has a distance of 0.05 R measured backward from the rear edge of the propeller in the axial direction. The marine propulsion device according to any one of claims 1 to 10, further comprising at least one stator fin extending radially inside the duct.   A ship provided with the marine propulsion device according to any one of claims 1 to 11.

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